In this study, CB2R activation by the selective agonist JWH133 ameliorated BLM-induced pulmonary fibrosis in mice through decreasing pulmonary fibrosis score and inhibiting inflammation-associated cytokines IL-6, TNF-α, and IL-1β as well as through decreasing Col-I, Col-III, α-SMA, and HYP levels possibly via hindering the FAK/ERK/S100A4 pathway. The gene discussed is IL1B; the disease is pulmonary fibrosis.